KR20090053694A - Illumination optical apparatus, exposure apparatus, and device manufacturing method - Google Patents

Abstract

The illumination optics is configured to irradiate the irradiated surface with the light beam from the light source. The illumination optical apparatus switches between the first prism group having a plurality of prisms, the second prism group having a plurality of prisms, the first prism group and the second prism group, and the first prism. The prism group switch which can arrange | position one of a group and said 2nd prism group in an optical path is provided. By moving at least one of the plurality of prisms included in one of the first and second prism groups disposed in the optical path in the optical axis direction, the luminous flux emitted from one of the first and second prism groups The upper limit of the rotational ratio of the luminous flux emitted from the first prism group by varying the annular magnification is greater than or equal to the lower limit of the rotational ratio of the luminous flux emitted from the second prism group, and is emitted from the second prism group. It is smaller than the upper limit of the rotation rate of the light beam.

Description

ILLUMINATION OPTICAL APPARATUS, EXPOSURE APPARATUS, AND DEVICE MANUFACTURING METHOD}

The present invention relates to an illumination optical apparatus, an exposure apparatus and a device manufacturing method.

In recent years, the speed of semiconductor processing speed and the miniaturization of electronic devices have been further progressed, and the demand for miniaturization of semiconductor device patterns is increasing. In the process of drawing a fine circuit pattern on board | substrates, such as a silicon wafer and a glass plate, photolithography technique becomes an essential technique.

In this lithography step, the desired pattern illuminates the reticle (original) patterned in advance, and the image is transferred onto the photosensitive substrate through the projection optical system. In the above description, the word "reticle" is used as the original plate, but in general, "reticle" is used when the projection optical system is a reduced optical system, and "mask" is used when the projection optical system is an equal magnification optical system. The present invention is not limited to the magnification of the projection optical system, but for easy understanding, the term "reticle" will be used hereinafter.

A semiconductor exposure apparatus can be mainly divided into two types of apparatuses, a step type exposure apparatus and a scan type exposure apparatus. The step type exposure apparatus has an advantage that the structure is relatively simple and the cost is reduced as compared with the scan type exposure apparatus. However, in order to expose a wide area, it is necessary to enlarge the exposure field of a projection optical system. Therefore, it is disadvantageous in terms of aberration correction.

On the other hand, a scanning exposure apparatus performs exposure, synchronously scanning a reticle and a photosensitive board | substrate. By scanning, the area larger than the exposure field of a projection optical system can be exposed. For this reason, there is an advantage that the size of the exposure field of the projection optical system can be reduced. Therefore, in view of the aberration correction of the projection optical system, the scan type exposure apparatus is superior to the step type exposure apparatus.

The resolution R of the exposure apparatus is expressed by the following formula (1), which is generally referred to as Rayleigh's formula.

In this equation (1), k1 is a process coefficient, λ is a light source wavelength of the exposure apparatus, and NA is a numerical aperture of the projection optical system. In accordance with Rayleigh's equation represented by Formula (1), in order to draw the fine circuit pattern by reducing the resolution R, it is necessary to reduce process coefficient k1 or wavelength (lambda), or to enlarge numerical aperture NA of a projection optical system.

In recent years, immersion exposure technology and the like have attracted attention as a means for increasing the numerical aperture NA of the projection optical system. However, in general, when the numerical aperture NA of the projection optical system is made larger, the projection optical system becomes larger or more complicated, leading to an increase in the cost of the exposure apparatus. The cost of the exposure light source with a small wavelength [lambda] becomes high. When an exposure light source having a small wavelength? Is used, the absorption and birefringence of the glass material are large, so that there is a problem that the efficiency is reduced and the desired image performance cannot be obtained.

As a means for reducing the resolution R without changing the light source wavelength or the numerical aperture NA of the projection optical system, there is a method called RET (Resolution Enhancement Technology) for reducing the process coefficient k1. For example, one of the techniques is a method of giving an auxiliary pattern or an offset of a line width to a reticle according to the optical characteristics of an exposure optical system.

As a means for obtaining an effect equal to or higher than the optimization of such a reticle, there is a means for optimizing the light intensity distribution of the pupil plane which is substantially related to the Fourier transform with the irradiated surface according to the reticle pattern. This is commonly called off-axis illumination. The light intensity distribution in the pupil plane and the conjugate plane of the pupil plane which are substantially related to the Fourier transform with the irradiated plane is generally called an effective light source.

As off-axis illumination, annular illumination and multipole illumination are the most common. The effective light source is often represented by an illumination parameter called "external σ", "internal σ", or "opening angle" as shown in FIG. Here, "external σ" corresponds to the outer diameter of the effective light source, and "internal σ" corresponds to the inner diameter of the effective light source, respectively. In addition, an "opening angle" is an angle formed by an irradiation section (opening section) with a point on the optical axis as a vertex.

A parameter called "rotation rate" is also often used. This is the ratio between the internal σ and the external σ, and is defined as internal σ / external σ. The optimal leap ratio depends on the reticle pattern. For this reason, it is preferable to comprise an exposure apparatus so that a ring ratio can be adjusted.

As a method of adjusting the circumference ratio, for example, Japanese Patent Laid-Open No. Hei 5-21312 discloses a method of arranging a stop having a circumferential shape in the vicinity of the pupil plane.

As another method of adjusting the ring ratio, Japanese Laid-Open Patent Publication No. Hei 5-251308 discloses a method of using a prism having a conical refractive surface. In this document, there is a description that it is preferable to configure the apparatus so that the interval between the concave prism and the convex prism can be set so as to set the rolling ratio in the range of 1/3 to 2/3.

In addition, as another method of adjusting the rotation ratio, Japanese Laid-Open Patent Publication No. 2001-35777 discloses a method of installing a focal length variable optical system, a conical prism, an adjustable axicon, and a zoom lens. have.

As disclosed in Japanese Patent Laid-Open No. Hei 5-21312, the method of arranging a ring-shaped diaphragm in the vicinity of the pupil plane has a problem that the efficiency of light used for exposure is reduced in order to shield the light beam. there was. Moreover, there was another problem that it was not possible to continuously adjust the rotation rate.

As disclosed in Japanese Patent Laid-Open No. Hei 5-251308, in the method of simply adjusting the interval between the concave prism and the convex prism, for example, the variable range of the rotator ratio is 1/2 or less to 3/4. It was difficult to achieve to the above. In this method, it is necessary to increase the inclination angle of the prism or increase the moving distance of the prism in order to increase the variable range of the rotational ratio. However, when the inclination angle of the prism is increased, the light transmittance is reduced due to the reflection of light or scattering, and sufficient efficiency cannot be obtained. In addition, when the moving distance of the prism is increased, the size of the apparatus is increased.

In the same method as disclosed in Japanese Patent Laid-Open No. 2001-35777, it is necessary to arrange a large number of optical elements in an optical path. Therefore, the apparatus is enlarged.

As described above, in the prior art, when the scaling ratio is continuously adjusted in a wide range, there is a problem that the efficiency is reduced or the apparatus is enlarged.

The present invention provides an illumination optical device capable of continuously adjusting the rotation ratio in a wide range. Moreover, this invention provides the illumination optical apparatus which can adjust a rotation ratio, suppressing the enlargement of an apparatus and the fall of the utilization efficiency of the light from a light source.

An illumination optical device as one aspect of the present invention is an illumination optical device configured to irradiate a light beam from a light source onto an irradiated surface. The illumination optical device switches between the first prism group having a plurality of prisms, the second prism group having a plurality of prisms, the first prism group and the second prism group, and the first prism. The prism group switch which can arrange | position one of a group and said 2nd prism group in an optical path is provided. By moving at least one of the plurality of prisms included in one of the first and second prism groups disposed in the optical path in the optical axis direction, the luminous flux emitted from one of the first and second prism groups The upper limit of the rotational ratio of the luminous flux emitted from the first prism group by varying the annular magnification is greater than or equal to the lower limit of the rotational ratio of the luminous flux emitted from the second prism group, and is emitted from the second prism group. It is smaller than the upper limit of the rotational ratio of the luminous flux.

An illumination optical device according to still another aspect of the present invention is an illumination optical device configured to irradiate an irradiated surface with a light beam from a light source. The illumination optical device includes a first prism group having a plurality of prisms and a second prism group having a plurality of prisms. The prism group of one of the first and second prism groups includes a first concave prism and a first convex prism disposed so that the inclined surfaces face each other, and the first concave prism and the first convex prism. By combining a prism, it has substantially the formation of a flat plate, and the other prism group of the said 1st and 2nd prism group is removable in the optical path of the said light beam. Luminous flux emitted from one prism group of the first and second prism groups by moving at least one of the plurality of prisms included in one prism group of the first and second prism groups in the optical axis direction The upper limit value of the rotation rate of the luminous flux emitted from the first prism group is changed by changing the rotation rate of the first prism group, and is equal to or more than the lower limit of the rotational ratio of the luminous flux emitted from the second prism group, and is emitted from the second prism group. It is smaller than the upper limit of the rotation rate of the luminous flux.

New objects or features of the present invention will be apparent from the preferred embodiments described below with reference to the drawings.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a diagram schematically showing a configuration of an exposure apparatus having an illumination optical device in one embodiment of the present invention. The illumination optical apparatus includes the optical member from the relay optical system 2 to the condenser optical system 11 described later. However, this illumination optics is not limited to this configuration.

The light source 1 is, for example, an ArF laser having a wavelength of about 193 nm or a KrF laser having a wavelength of about 248 nm. However, the present invention is not limited to the type, wavelength, or number of light sources. The light source is not limited to laser. You may employ | adopt non-laser light sources, such as a mercury lamp.

The relay optical system 2 enlarges or reduces the luminous flux from the light source 1 and introduces the luminous flux into the beam shaping optical system 3 in a state of substantially parallel light.

The beam shaping optical system 3 is composed of a plurality of optical elements, a zoom optical system, and the like. The beam shaping optical system 3 controls so that the intensity distribution and the angular distribution of the light beam incident on the optical integrator 4 at the rear end become a desired distribution. The detailed function of the beam shaping optical system 3 will be described later.

The optical integrator 4 is, for example, a micro lens array in which a plurality of refractive optical elements, reflective optical elements, or diffractive optical elements such as Fresnel lenses are two-dimensionally arranged. In addition, the optical integrator 4 may be a computer hologram (CGH: Computer Generated Hologram) designed to obtain a desired pattern. The light beam emitted from the optical integrator 4 is condensed by the condenser optical system 6, and illuminates the surface on which the traveling field stop 8 is located in an overlapping manner.

The light blocking member 5 is disposed near the exit surface of the optical integrator 4. The surface where the light shielding member 5 is located is in an air space relation with the pupil plane of the projection optical system 14, and various off-axis illuminations can be formed according to the shape of the light shielding member 5. .

Referring to FIG. 3, an example of a specific switching mechanism of the light blocking member 5 will be described. The light blocking member 5 is formed by arranging a plurality of diaphragms having different shapes on the circular substrate 500. The board | substrate 500 is comprised so that the point O can rotate as a center of rotation so that one of the apertures 501, 502, 503 may be located in an optical path.

The stop 501 is a normal aperture stop. The iris 502 is an iris for dipole lighting. The iris can be formed by cutting a beam of light from conventional lighting, circular lighting, and the like. Aperture 503 is an aperture for quadrupole illumination, and it is possible to form quadrupole illumination by cutting a beam of light from conventional illumination, circular illumination, and the like.

The photosensitive member 7 is, for example, a concentration filter or a metal blade. By controlling the movement or rotation of the photosensitive member 7, it is possible to adjust the light intensity distribution reaching the irradiated surface.

The traveling visual field stop 8 is arrange | positioned in the position conjugated with the to-be-irradiated surface in which the reticle 12 (original plate) is located. The traveling field stop 8 includes a plurality of movable light shielding plates, and regulates the illumination range of the irradiated surface by arbitrarily controlling the opening shape.

The luminous flux that has passed through the traveling visual field stop 8 is introduced into the irradiated surface by the condenser optical system 9, the mirror 10, and the condenser optical system 11.

The reticle 12 is held by the reticle stage 13. The pattern drawn on the reticle 12 arranged on the irradiated surface is transferred to the wafer 15 located on the exposure surface by the projection optical system 14.

The wafer stage 16 holds the wafer 15 and is controlled to move in two dimensions along the optical axis direction and a plane orthogonal to the optical axis.

In the scanning exposure method, the scanning exposure is performed while the reticle 12 and the wafer 15 are synchronized in the arrow direction (left and right directions) in FIG. 2. When the reduction magnification of the projection optical system 14 is 1 / β, when the scanning speed of the wafer stage 16 is V, the scanning speed of the reticle stage 13 is βV.

(Example 1)

Next, with reference to FIG. 1, the structure of the beam shaping optical system 3 in Example 1 is demonstrated in detail.

The light beam introduced into the beam shaping optical system 3 from the relay optical system 2 is incident on the diffractive optical element 301. The diffractive optical element 301 is, for example, a calculator hologram designed to obtain a desired pattern.

The light beam emitted from the diffractive optical element 301 is collected by the condenser optical system 303, and forms a circular pattern on the Fourier transform surface 304.

The light beam passing through the Fourier transform surface 304 is incident in the order of conical concave prism 305a (first concave prism) and conical convex prism 306a (first convex prism).

The first prism group consisting of the conical concave prism 305a and the convex convex prism 306a is converted to the second prism group consisting of the conical concave prism 305b (second concave prism) and the conical convex prism 306b (second convex prism). It is configured to be. The switching of the prism group is performed by the prism group switch 308. In this way, the prism group switch 308 switches the first prism group and the second prism group so as to position one of the first and second prism groups in the optical path.

The conical concave prisms 305a and 305b and the conical convex prisms 306a and 306b have complementary refraction effects. For this reason, when light rays parallel to the optical axis are incident on the conical concave prisms 305a and 305b, the light rays are refracted by the concave concave prisms 305a and 305b and conical convex prisms 306a and 306b and then conical convex prisms 306a and 306b parallel to the optical axis. Is injected from.

The prism moving means 309 includes at least one of a concave prism and a convex prism constituting any one of a prism group selected from the first prism group and the second prism group introduced into the optical path by the prism group switch 308. Move it. For this reason, at least one of the conical concave prisms 305a and 305b and the convex convex prisms 306a and 306b is configured to be movable in the optical axis direction. Thus, by changing the relative positions of the conical concave prisms 305a and 305b and the conical convex prisms 306a and 306b by using the prism moving means 309, the rotation rate of the light beam emitted from the prism group can be adjusted.

The light beam emitted from the prism group is enlarged or reduced while maintaining the substantially similar shape by the zoom optical system 307, and is introduced into the optical integrator 4 from the beam shaping optical system 3. For this reason, the rotation rate of the light beam emitted from the zoom optical system 307 is approximately equal to the rotation rate of the light beam incident on the zoom optical system 307.

Conical concave prisms 305a and 305b and conical convex prisms 306a and 306b have an inclined surface that is inclined at a predetermined angle. The inclination angles of the conical concave prism 305a and the convex convex prism 306a are approximately equal to each other, and each of these prisms has an inclination angle α. Similarly, the inclination angles of the conical concave prism 305b and the convex convex prism 306b are also substantially the same, and each of the prisms has an inclination angle β.

It is preferable that the inclination angle α of the conical concave prism 305a and the convex convex prism 306a is smaller than the inclination angle β of the conical concave prism 305b and the conical convex prism 306b. In this case, the refractive action of the conical concave prism 305a and the conical convex prism 306a is smaller than that of the conical concave prism 305b and the conical convex prism 306b.

The conical concave prism 305a and the conical convex prism 306a are arranged so that the inclined surfaces having the refractive action face each other. On the other hand, the concave concave prism 305b and the convex convex prism 306b are arranged so that the inclined surfaces having the refractive action are directed in opposite directions to each other.

Next, the difference between the range of the roundness that can be adjusted by the conical concave prism 305a and the convex prism 306a and the range of the roundness that can be adjusted by the conical concave prism 305b and the conical convex prism 306b are shown in FIGS. 5 and 6. This will be described with reference to.

5A and 5B are diagrams schematically showing the range of the circumferential ratio that can be adjusted by the conical concave prism 305a and the conical convex prism 306a.

The inclined surfaces of the conical concave prism 305a and the conical convex prism 306a constituting the first prism group are arranged to face each other. When the conical concave prism 305a and the convex prism 306a are combined, i.e., when the distance between both prisms is zero, as shown in Fig. 5A, the first group of prisms (conical concave prism 305a and convex prism 306a) is planar. Form the plate. In practice, it is difficult to adjust the spacing between both prisms to zero because interference of the prism must be avoided. However, if the spacing between both prisms is a finite small value, the first group of prisms can be regarded as substantially flat plates. In this case, the optical action of the first group of prisms is substantially the same as that of the flat plate. For example, when the circular luminous flux (incident light flux) shown on the left side of FIG. 5A is incident on the first prism group, as shown on the right side of FIG. 5A, the circular luminous flux (injection light flux) same as the incident luminous flux is emitted. do.

As shown in FIG. 5B, when the space | interval of the conical concave prism 305a and conical convex prism 306a which comprise a 1st prism group is changed widely, a ring-shaped injection light beam can be obtained. When the distance between the conical concave prism 305a and the convex convex prism 306a is changed widely, and the circular beam (incident light beam) shown on the left side of FIG. 5B is incident on the first prism group, a circular-shaped shape as shown on the right side of FIG. 5B is obtained. A luminous flux (injection luminous flux) is formed on the exit surface. In this manner, as the relative distance between the conical concave prism 305a and the convex convex prism 306a increases, the rotation rate of the light beam emitted from the first prism group increases.

5A and 5B, when the inclined surfaces of the conical concave prism 305a and the convex convex prism 306a are disposed to face each other, the inclination angle of the prism is set to 25 degrees or less, and more preferably 20 degrees or less. If the inclination angle of the prism is θ, the glass material refractive index of the prism is n, and the emission angle of the light ray with respect to the normal of the prism inclined plane is θ ', the ejection angle θ' is obtained according to equation (2) representing Snell's law. Can be calculated

sinθ '= nsinθ (2)

Generally, the glass material refractive index n is about 1.5. For this reason, when the inclination angle θ of the prism is 25 °, the emission angle of the light beam is 39.34 °, and when the inclination angle θ of the prism is 20 °, the light emission angle of the light beam is 30.87 °. If the incident angle and the exit angle of the light beam are large, the amount of reflected and scattered light increases, and the efficiency also decreases. As a result, the desired light intensity distribution cannot be obtained.

When the inclination angle θ of the prism is very small, the distance between the conical concave prism 305a and the convex convex prism 306a must be widened to form a thin annular beam having a large annular ratio. In this case, however, the apparatus is enlarged.

As another method for forming a large, thin, annular light beam having a circular ratio, there is also a method of injecting a small circular light beam. In this case, however, the energy density of the light is increased, which increases the consumption of the optical system.

At the center of the prism, there is an unstable area where it is difficult to machine the prism. 5A and 5B schematically show an ideal conical prism. However, in reality, there are unstable areas such as rounded, recessed, translucent and so on in the vertex portion. When a small circular light beam is incident, the proportion of light passing through this unstable region is increased. For this reason, efficiency falls and a desired light intensity distribution cannot be obtained.

As described above, according to the configuration shown in Figs. 5A and 5B, the rolling ratio can be continuously adjusted from 0 to 2/3 or more (first range) without causing a decrease in efficiency and an increase in size of the apparatus.

6A and 6B show an example of the range of the rotator ratio that can be adjusted by the conical concave prism 305b and the conical convex prism 306b.

The inclined surfaces of the conical concave prism 305b and the conical convex prism 306b constituting the second prism group are arranged to face in opposite directions to each other. For this reason, as shown in FIG. 6A, when the space | interval between both prisms is set to zero, and the circular beam (incident light beam) shown to the left of FIG. 6A is made to inject, the emitted light beam emitted from the convex convex prism 306b will be the same as that of FIG. 6A. It has a circular belt shape as shown on the right. When the concave concave prism 305b and the convex convex prism 306b constituting the second prism group are combined to arrange the inclined surfaces of both prisms facing each other, these prisms have a relationship to form a flat plate. This point is the same as that of the first prism group.

As shown in FIG. 6B, when the space | interval between the conical concave prism 305b and the conical convex prism 306b which comprise a 1st prism group is changed widely, a further thin annular beam speed can be obtained. The spacing between both prisms shown in FIG. 6B is the same as that of the prism in FIG. 5B. As shown in FIG. 6B, when the interval between both prisms is changed widely and the circular beam (incident light beam) shown on the left side of FIG. 6B is incident, as shown on the right side of FIG. 6B, A annular beam (injection light beam) is formed on the exit surface. In this manner, as the relative distance between the conical concave prism 305b and the convex convex prism 306b increases, the rotation rate of the light beam emitted from the second prism group increases.

As shown in Figs. 6A and 6B, when the concave concave prism 305b and the convex convex prism 306b are disposed so that the inclined surfaces thereof face each other in opposite directions, the inclination angle of the prism can be made larger than when the inclined surfaces face each other. There is a number. This is because when the inclined surface of the prism is arranged in the opposite direction, the incident angle and the exit angle of the parallel light beam with respect to the prism coincide with the inclined angle of the prism. Therefore, when arranging the inclined surface of the prism in the opposite direction, even if the inclination angle of the prism is 30 degrees or more, the amount of reflecting and scattering light is relatively small.

In this embodiment, the upper limit of the rotational ratio of the luminous flux emitted from the first prism group is greater than or equal to the lower limit of the luminous flux emitted from the second prism group and is smaller than the upper limit of the luminous flux emitted from the second prism group.

As such, the roundness ratio when the distance between the conical concave prism 305b and the conical convex prism 306b is zero is equal to or smaller than the roundness ratio when the gap between the conical concave prism 305a and the convex convex prism 306a is maximized. It is preferable to set it to This is because the rotation rate is set to change continuously, and the rotation rate can be adjusted continuously.

According to the configuration shown in Figs. 6A and 6B, the scaling ratio can be continuously adjusted from 2/3 or less to 4/5 or more (second range) without causing a decrease in efficiency or enlargement of the apparatus. The second range, unlike the first range, includes a value (rotation rate) that is greater than at least the value included in the first range. Therefore, by combining with the prism shown to FIG. 5A and 5B, it becomes possible to adjust a widening ratio extensively from zero to 4/5 or more.

As described above, according to the present embodiment, the first prism group used to continuously adjust the rotator ratio in the first range and the second prism group used to continuously adjust the rotator ratio in the second range. Is installed. When the first group of prisms is introduced into the optical path, the rotation rate of the light beam emitted from the first group of prisms is continuously adjusted in the first range by the prism moving means 309. When the second group of prisms is introduced into the optical path, the rotational ratio of the light beam emitted from the second group of prisms is continuously adjusted in the second range by the prism moving means 309.

In the above description, the first prism group and the second prism group can be selectively introduced into the optical path by the prism group switch. It is also possible to provide another optical system configured to be switched and introduced by a prism group switch.

In addition, the present embodiment may be configured such that the first prism group (one prism group) is always arranged in the optical path, and only the second prism group (another prism group) can be detached from the optical path. In this configuration, when the first prism group obtains light of a desired round ratio, the second prism group is disposed outside the optical path. On the other hand, when the light of desired rotational ratio is obtained by the 2nd prism group, a 1st prism group is comprised so that it may become a flat plate state combining a 1st concave prism and a 1st convex prism. If comprised in this way, even if the 1st prism group is arrange | positioned in an optical path, it will be in the state which a 1st prism group does not exist substantially from a viewpoint of a rolling ratio. Thus, the structure which moves only a 2nd prism group between the inside of an optical path and the outside of an optical path can also be employ | adopted.

As described above, according to the present embodiment, the scaling ratio can be continuously adjusted in a range between at least 1/2 and 4/5 while suppressing the enlargement of the device with high efficiency.

(Example 2)

Next, with reference to FIG. 9, the beam shaping optical system 3 in Example 2 is demonstrated in detail. According to the structure of this embodiment, compared with Example 1, it becomes possible to further widen the adjustment range of a rotation ratio.

In the present embodiment, like the first embodiment, the first prism group and the second prism group are configured to be switchable. Therefore, optionally, one of these groups of prisms can be introduced into the optical path.

In this embodiment, a plurality of diffractive optical elements 301a and 301b are mounted on a turret 302, and optionally one of these diffractive optical elements can be introduced into the optical path.

The light beam supplied from the light source 1 is incident on any one of the plurality of diffractive optical elements 301a and 301b. The plurality of diffractive optical elements 301a and 301b are mounted on the turret 302, and one of the diffractive optical elements 301a and 301b is configured to be selectively introduced into the optical path. The selection of any of the diffractive optical elements 301a and 301b is made by the diffractive optical element selector 310 which rotates the turret 302. In Fig. 9, two diffractive optical elements 301a and 301b are shown. However, the number of diffractive optical elements is not limited to this. Three or more diffractive optical elements may be provided.

When the calculator hologram is used as the diffractive optical element, the optical intensity distribution of any shape corresponding to each diffractive optical element can be formed on the Fourier transform surface 304 of the calculator hologram through the condenser optical system 303. The pattern formed on the Fourier transform surface 304 is, for example, circular, annular, multipole or the like.

Next, an example of a specific switching mechanism of the diffractive optical element will be described with reference to FIGS. 4A and 4B.

As shown in FIG. 4A, the turret 302 is provided with a plurality of diffractive optical elements 301a, 301b, 301c, and 301d. The turret 302 is configured to be rotatable about the point O such that one of the four diffractive optical elements 301a, 301b, 301c, and 301d provided on the turret 302 is located in the optical path. The rotation of the turret 302 is driven and controlled by the diffractive optical element selector 310.

As shown in FIG. 4B, the diffractive optical elements 301a and 301c form a circular pattern on the Fourier transform surface 304. The diffractive optical element 301b forms a ring-shaped pattern on the Fourier transform surface 304. The diffractive optical element 301d forms a quadrupole pattern on the Fourier transform surface 304.

Next, with reference to FIGS. 7A and 7B, the adjustment range of the annular ratio in the case where the annular light beam enters the conical concave prism 305a and the convex convex prism 306a will be described.

The inclined surfaces of the conical concave prism 305a and the convex convex prism 306a are arranged to face each other. For this reason, as shown in FIG. 7A, when the space | interval between both prisms is zero, optical action becomes the same as that of a flat plate. In practice, it is difficult to adjust the distance between both prisms to zero because interference of the prism must be avoided. However, by setting the spacing between both prisms to a finite small value, the first group of prisms can be regarded as substantially flat plates. In this case, as shown in the right side and the left side of FIG. 7A, the change in the circular ratio is small between the incident light beam and the emitted light beam.

On the other hand, as shown in FIG. 7B, when the space | interval between the conical concave prism 305a and the convex convex prism 306a is widened, as shown in the right side of FIG. 7B, the rotational ratio of an injection light beam will become large and a thinner annular injection beam can be obtained.

When a circular light beam enters the concave concave prism 305a and the convex convex prism 306a using the diffractive optical element 301a, as shown in Figs. 5A and 5B, the rotation ratio can be changed from zero to 2/3 or more. If the minimum value of the circularity of the annular pattern formed on the Fourier transform plane is set to 2/3 or less, the diffraction optical element 301b changes the spacing between the conical concave prism 305a and the convex convex prism 306a, thereby reducing the circularity ratio to 2/3. It can be changed from 4/5 to below. Therefore, by switching the diffractive optical element 301a and the diffractive optical element 301b using the diffractive optical element selector 310 and adjusting the spacing of the prism by using the prism moving means 309, the rotator ratio from zero to 4/5 or more. I can adjust it.

Next, with reference to FIGS. 10A and 10B, an adjustment range of the annular ratio when the annular light beam enters the conical concave prism 305b and the conical convex prism 306b will be described.

The inclined surfaces of the conical concave prism 305b and the conical convex prism 306b face each other in opposite directions. For this reason, even if the distance between both prisms is zero as shown in Fig. 10A, the emitted light flux emitted from the conical convex prism 306b shown on the right side of Fig. 10A has a annular shape that is thinner than the incident light beam shown on the left side of Fig. 10A.

As shown in FIG. 10B, when the interval between the conical concave prism 305b and the convex convex prism 306b is changed widely, a thinner annular beam can be obtained. As shown on the left side of Fig. 10B, when the annular incident light beam is incident on the prism group, as shown on the right side of Fig. 10B, a narrow annular injection beam with a radius of 5/6 or more is formed on the exit surface. .

As described above, according to the present embodiment, it is possible to continuously adjust the rolling ratio in a wider range while suppressing the enlargement of the device with high efficiency.

By the way, when the diffractive optical element 301d is introduced into the optical path, a multipole pattern is formed on the Fourier transform surface 304. In this case, if the distance between the pair of cone prisms is changed, even if the ratio of the external σ and the internal σ can be adjusted, the opening angle of each pole cannot always be controlled. This is because the conical surface has a refractive action in the circumferential direction, and the pole shape formed on the Fourier transform surface 304 deforms in the circumferential direction from the conical surface.

From this point of view, according to the inventor's study, in order to reduce the change in the opening angle, it is preferable to set the numerical aperture NA of the light beam incident on the conical prism to 0.1 or less, and the diameter φ of the light beam incident on the conical prism is set. It is preferable to set it to 20 mm or more. Moreover, it is preferable to set the vertex angle (theta) of a cone prism to 20 degrees or less. For this reason, it is preferable that at least one prism satisfy | fills the said condition among the prism provided in the beam shaping optical system 3 of the said Example.

In the above embodiment, a conical prism is used as the prism. However, a pyramid prism, a deformed conical prism whose center is a planar surface, etc. can also be used as needed, such as when forming complex off-axis illumination, such as a multipole illumination.

In the above embodiment, a micro lens array or a diffractive optical element is used as the optical integrator. However, other integrators, such as a rod type integrator, can also be used.

A device such as a semiconductor element or a liquid crystal display element includes a process of exposing a substrate (wafer, glass plate, etc.) coated with a photosensitive agent using the exposure apparatus of some of the above-described embodiments, a process of developing the substrate, and other well-known It is manufactured by going through a process.

According to the device manufacturing method described above, a high quality device can be manufactured. In this manner, the device manufacturing method using the above exposure apparatus and the device as a result also constitute one aspect of the present invention.

According to the above embodiment of the present invention, it is possible to provide an illumination optical device capable of adjusting the scaling ratio in a wide range and continuously. In particular, it is also possible to provide an illumination optic that is configured to adjust the wheel scale between at least 1/2 and 4/5. According to the embodiment described above, it is possible to efficiently adjust the ring size while suppressing the enlargement of the apparatus.

As mentioned above, although preferred embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to this exemplary embodiment, A various deformation | transformation and a change are possible within the scope of the summary.

For example, the prism is not limited to the convex prism and the concave prism described in the above embodiments. Optical members such as diffractive optical elements having the same effect as prisms can also be used.

The arrangement of the conical surface (inclined surface) of the prism is not limited to the arrangement illustrated in FIGS. 5 and 6. Any conical surface may be arranged on the light source side with respect to the prism, or may be arranged on the irradiated surface side with respect to the prism. For example, with respect to the positional relationship between the first concave prism constituting the first prism group and the first convex prism, the first concave prism is disposed on the side to be irradiated, and the first convex prism is a light source. Is placed on the side. Both conical surfaces of the first concave prism and the first convex prism are disposed on the light source side. As for the positional relationship between the second concave prism and the second convex prism constituting the second prism group, the second concave prism is arranged on the light source side, and the second convex prism is arranged on the irradiated surface side. do. The conical surfaces of the second concave prism and the second convex prism are both disposed on the irradiated surface side.

1 is a schematic diagram of a beam shaping optical system according to a first embodiment of the present invention.

2 is a schematic diagram of an exposure apparatus including an illumination optical apparatus in an embodiment of the present invention.

3 is a schematic view of the light blocking member in the embodiment of the present invention.

4A and 4B are schematic views of diffractive optical elements in the embodiment of the present invention.

5A and 5B are explanatory views of the first prism group in the first embodiment of the present invention.

6A and 6B are explanatory views of the second prism group in the first embodiment of the present invention.

7A and 7B are explanatory diagrams of a change in the rolling ratio in the second embodiment of the present invention.

8 is an explanatory diagram for a parameter of an effective light source.

9 is a schematic diagram of a beam shaping optical system according to a second embodiment of the present invention.

10A and 10B are explanatory diagrams of a change in the rolling ratio in the second embodiment of the present invention.

Claims (8)

An illumination optical device configured to irradiate a light beam from a light source onto an irradiated surface, A first prism group having a plurality of prisms, A second group of prisms having a plurality of prisms, And a prism group switch capable of switching the first prism group and the second prism group to arrange one of the first prism group and the second prism group in an optical path, By moving at least one of the plurality of prisms included in one of the first and second prism groups disposed in the optical path in the optical axis direction, the luminous flux emitted from one of the first and second prism groups Change the leap rate, The upper limit of the rotational ratio of the luminous flux emitted from the first prism group is greater than or equal to the lower limit of the luminous ratio of the luminous flux emitted from the second prism group, and the upper limit of the rotational ratio of the luminous flux emitted from the second prism group. Illumination optics, characterized in that smaller. The method of claim 1, The first group of prisms includes a first concave prism and a first convex prism arranged so that the inclined surfaces face each other, The second group of prisms includes a second concave prism and a second convex prism disposed so that the inclined surfaces face in opposite directions to each other, And at least one of a concave prism and a convex prism included in one prism group of the first and second prism groups disposed in the optical path is movable in an optical axis direction. The method of claim 2, The first optical prism group is configured to be a substantially flat plate by combining the first concave prism and the first convex prism. The method of claim 1, A plurality of diffractive optical elements configured to diffract a light beam from the light source and to enter a group of prisms disposed in the optical path; A diffractive optical element selector configured to select one of the plurality of diffractive optical elements and to place in the optical path; And a condenser optical system configured to condense the light beam emitted from the diffractive optical element disposed in the optical path, And the rotation ratio is adjusted by switching the diffractive optical element in which the diffractive optical element selector is arranged in the optical path. The method of claim 2, The inclination angle of the second concave prism is larger than the inclination angle of the first concave prism. An illumination optical device configured to irradiate a light beam from a light source onto an irradiated surface, A first prism group having a plurality of prisms, A second prism group having a plurality of prisms, The prism group of one of the first and second prism groups includes a first concave prism and a first convex prism disposed so that the inclined surfaces face each other, and the first concave prism and the first convex prism. By combining the prisms to substantially form the flat plate, The other prism group of the first and second prism groups is detachable from the optical path of the light beam, Ejected from one prism group of the first and second prism groups by moving at least one of the plurality of prisms included in one prism group of the first and second prism groups in the optical axis direction Change the luminous flux of the beam, The upper limit of the rotational ratio of the luminous flux emitted from the first prism group is greater than or equal to the lower limit of the luminous ratio of the luminous flux emitted from the second prism group, and the upper limit of the rotational ratio of the luminous flux emitted from the second prism group. Illumination optics, characterized in that smaller. The illumination optical device according to any one of claims 1 to 6, And a projection optical system configured to project an image of a pattern of the original plate disposed on the irradiated surface onto a substrate. Exposing the substrate using the exposure apparatus according to claim 7, A device manufacturing method comprising the step of developing the exposed substrate.

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